Descriptions

An important field of study within the exercise science realm lies in identifying risk factors for musculoskeletal injuries to inform injury prevention programs. One of the more serious injuries in sports, especially sports involving cutting and jumping, is sprain of the anterior cruciate ligament (ACL). Previous research has found that women are at greater risk for ACL injuries and this injury most commonly occurs during a deceleration movement.
For this study, we measured landing biomechanics before and after an exercise protocol to gain insight on the influence of fatigue on knee position and loading during a single leg jump-cut and a double leg jump landing. Forty female participants between the ages of 18-30 who were free of musculoskeletal injury, had no history of ACL injury, and engaged in at least 150 minutes of moderate exercise per week were enrolled. Subjects performed two landing tasks: 1) a double leg landing from a 30 cm high box placed a distance of 50% of their height from the edge of two force platforms and 2) a single leg jump-cut over a small hurdle from a distance of 50% of their max height behind the force platforms prior to completing an exercise protocol. For the exercise protocol, subjects performed 6 cycles of treadmill walking at a self-selected speed between 3.0-3.5 mph for 5 minutes followed by one minute of jumping activities. Following the 30-minute exercise protocol, landing biomechanics were again measured as the subjects repeated the two landing tasks.
The results presented in this poster will compare changes in single leg jump-cut and double leg jump landing biomechanics due to exercise. The specific variables of interest are: knee flexion angle at initial contact, peak internal knee extension and varus moments, knee valgus angle at initial contact, and peak knee valgus angle. These factors have previously been identified as significant predictors of ACL injury. By comparing the effects of exercise on knee biomechanics throughout both the single leg jump-cut and the double leg jump landing tasks we aim to identify if the biomechanical changes that occur from exercise are similar between tasks or if they are task dependent.